An outer assembling mechanism of a backpack for carrying a detachable skate. The mold-release agents of the invention, which are preferably based on suspensions of nanostructured microparticles, have the advantage of being markedly more environmentally compatible than the known mold-release agents based on organic or organosilicon compounds, since they can remain on the surfaces of the moldings. The active load circuit may be based on two active devices connected to the buffer output so as to form a differential cascode circuit. A first optimum recording power obtaining part performs test recording on the optical disk while the optical disk is rotated by the driver and output power of the light emitting element is varied so as to obtain an optimum recording power based on a reproduction signal in a test recorded area. The panels may be used to fabricate a fence.